Electric plug



Dec. 23, 1958 J. D. BALDRIDGE 2,856,170

ELECTRIC PLUG Filed March 27, 1957 I NVENTOR. (/AMES 0- BALD/W062 United States PatentO ELECTRIC PLUG James D. Baldridge, Merritt Island, Fla. Application March 27, 1957, Serial No. 648,953

2 Claims. 01. 339-99 This invention relates to electric plugs. More particularly, the invention relates to plugs of the insulationpiercing type, having so-called quick-connect or screwless terminals.

It is an object of the present invention to provide an inexpensive, yet strong plug characterized by the ease with which the leads of an electric conductor or appliance cord may be inserted in and held in engagement by the insulation-piercing terminals.

It is another object of the present invention to provide a plug that will cause the grip of the-terminals upon the leads or wires to become stronger in direct proportion to a pull exerted on the conductor tending to separate the same from the body of the plug.

It is a further object to eliminate moving parts, with an attendant reduction in manufacturing costs, so as to improve upon screwless, insulation-piecing, electric plugs previously devised.

For other objects and a better understanding of the invention, reference may be had to the following detailed description taken in connection with the accompanying {drawing in which:

i Figure 1 is a longitudinal sectional view through an electric plug according to the present invention as it appears with the electric cord connected thereto;

Fig. 2 is a side elevational view of the plug;

Fig. 3 is a diagrammatic view on an enlarged scale showing the mode of engaging one of the wires with its associated terminal, the wire being illustrated immediately before entering between the gripping teeth; and

Fig. 4 is a view similar to Fig. 3 in which the wire has been engaged between the teeth.

Referring now more in detail to the drawing, the plug constituting the invention includes a molded body of soft rubber, plastic, hard rubber, or other electrically insulative material, having a tapered rear end portion 12. Embedded in the body 10 are transversely spaced prongs 14 of electrically conductive metal material, projecting forwardly from the forward end of the body for engagement in the prong-receiving slots of a conventional electrical receptacle or female plug, not shown. The prongs 14 are formed, adjacent their forward ends, with the usual openings 16 arranged to provide means for engaging detents, latching projections, or equivalent elements in the socket or receptacle into which the device is to be plugged.

Within body 10, the prongs are integral with, and in fact constitute extensions of, elongated, straight,parallel shanks 18 embedded in the body. Shanks 18, at their inner ends, merge into bifurcations 19 having fork arms i 20. The arms 20 of each bifurcation 19 diverge in a direction away from the associated, connected shank 18, thus defining between the arms 20 of each bifurcation, i wedging spaces progressively reduced in width in a direction toward the convergent ends of the arms 20.

I 'Each arm 20 is formed, at uniformly spaced locations along the length thereof, with teeth 22. The teeth of i each arm are aligned, transversely of the'arn'l's, with the 2,866,170 Patented Dec. 23, 1958 corresponding teeth of the other arm, and initially, the teeth are curved toward the inner, narrower ends of the wedging spaces, when consideredin the sense of direction from the anchored or inner ends of the teeth toward the free or outer ends thereof.

The teeth are struck out of the material of the arms 20, though they may be otherwise formed, and are of at least a slight springability, so as to permit the teeth to resiliently yield to the passage of a wire between the teeth of each pair of transversely aligned, corresponding teeth. i

The bifurcations 19, at their wider ends, are spaced apart within the tapered end portion 12 to provide an entrance space 26 common to both of the terminals defined by the tooth-provided bifurcations.

A tubular rivet or grommet 28, having flanged ends or heads engaged against opposite faces of the body, is

extended through the space 26, wholly out of contact with the respective bifurcations, and has in its side wall a small aperture 29, opening toward the rear or smaller end of the body. A conductor or electric cord is of thoroughly conventional formation, and thus includes the side-by-side wires each of which has a sheath 30 of insulation in which is embedded the conductive lead 32.

In use, the cord is pushed through an opening 34 formed in the smaller, rear end of the body, said opening being aligned with aperture 29 of the grommet. There is no necessity of baring or stripping the wires 30 before extending the same through the opening.

One will now be able to observe the ends of the wires through the grommet, and by inserting through either end of the grommet a pencil tip, pin, or other thin, sharply pointed member, can divert one wire toward one bifurcation 19 and the other wire toward the other bifurcation. Once the wires have been led into the wedging spaces of the respective bifurcations, the cord is pushed further into the body 10. This causes the wires to enter the spaces between the teeth 22, in the manner shown in Figure 3. As the wires pass between the teeth of each pair, they will force the teeth away from each other to produce between them enough space for passage of the wire. The teeth will of course tend to spring back into place and being sharply pointed, will bite into or pierce the insulation so as to make contact with the leads 32 of the respective wires.

If an effort is made to pull the wires out, the teeth will merely bend to the positions shown in Figure 1, and will be caused in this way to bite even more firmly into the wires, so as to prevent retrograde movement of the wires out of the wedge-shaped spaces.

It thus becomes apparent that the pull that is often exerted on an electric cord, for the purpose of disengaging its plug from a receptacle or socket, will only cause the wires of the conductor to engage more firmly in the body, maintaining full electric contact between the wires and the terminals of the plug. An inexpensive plug, characterized by its lack of moving parts and by the ease and speed with which a wire can be connected thereto, is thus provided.

It will be understood that although a male plug is shown by way of example, the invention could be embodied in a female plug if desired.

While various changes may be made in the detail construction, it shall be understood that such changes shall be within the spirit and scope of the present invention as defined by the appended claims.

What I claim as new and desire to protect by Letters Patent of the United States is:

1. An electric plug comprising, in combination, a main body portion of electrically insulated material, connector means carried by the .body for effecting an electrical connection with a complementary electrical wiring device,

:said .connector means including wiring terminals, 'each said terminal including. a VV-shaped bifurcation forming :space,.said gripping means comprising teeth carried by each bifurcation, the teeth of each bifurcation being aligned transversely of and projecting laterally toward each other from the respective arms of the bifurcation and being inclined in the direction of insertion of the wire to thereby prevent its withdrawal, the wiring terminals converging and being spaced apart ,at their convergent ends to define an entrance space common to both bifurcations into which entrance space. the wires may be inserted be- 4 fore passing into the wedge shaped spaces, and said wedge shaped spaces communicating at their larger ends with the entrance space.

2. An electric plug according to claim 1, further including a tubular member extending through said entrance space and opening upon opposite faces of the body for providing access openings communicating said entrance space with said opposite faces of the body.

References Cited in the file of this patent UNlTED STATES PATENTS 2,291,434 Hollopeter July 28, 1942 2,618,680 Cook Nov. 18, 1952 2,745,077 Cook May 8, 1956 2,809,365 Broske Oct. 8, 1957 2,810,894 Kerr Oct. 22, 1957 

